chart colors & customisation

[gpalade]

Hy,
i'm using c# to create a powerPoint presentation that contains charts. I've added the chart(s) using Graph.Chart, it looks like this:

 Graph.Chart objChart = (Graph.Chart)objSlide.Shapes.AddOLEObject(xx, yy, 250, 180,
                    "MSGraph.Chart.8", "", MsoTriState.msoFalse, "", 0, "", MsoTriState.msoFalse).OLEFormat.Object;
            objChart.ChartType = Graph.XlChartType.xl3DColumnClustered;
 

I've added data using : dataSheet = objChart.Application.DataSheet;

Now my problem is that i need to set the color for the chart(i need the columns to be red, and by default there are blue), and i can't find any way to do that. I've tried with objChart.set_Colors but it doesn't work.

Anyone has any idea how can i do that?

Thanks!